Dear Lee,

Climate models are designed by implementing atmospheric primitive equations in the hydrostatic mode. The hydrostatic mode means that the atmosphere is in hydrostatic equilibrium/balance. In keeping this balance hydrostatic equations of fluid motion are solved for the vertical motion and by doing this vertical accelerations of fluid between model grids are kept very small (almost negligible). In other words this balance (approximation) is based on the assumption that the horizontal scale is large compared to the vertical scale and that is why we say that the hydrostatic condition hold for coarse resolutions model down to 10 km (not fixed). Below this resolution the hydrostatic equilibrium does not hold and the non-hydrostatic mode is applicable and the models dynamics needs major changes from hydrostatic mode to non hydrostatic mode. Therefore meso-scale models (like WRF/MM5) model are usually used for high resolution simulation which used non hydrostatic dynamics (the vertical momentum equation is solved) and the vertical motion between the grid boxes is allowed and solved dynamically. So if you want to run RegCM3 on very high resolution most probably your simulation will crashed either you use detail topography/land use data. You have to play with core dynamics of the RegCM3 model to make it work for non hydrostatic mode. If you want to run high resolution experiment I think the best way is to go for meso-scale model.

Cheers

Siraj

PhD student
Environmental Science and Engineering,
University of Northern British Columbia,
Prince George, BC, Canada